The central focus of this project is the study of the appearance, utilization, and decay of specific messenger RNAs coding for a family of structural proteins comprising the silkmoth eggshell. The sequential production of these cell-specific proteins, which are synthesized by the ovarian follicular epithelium at terminal differentiation, represents an exquisitely coordinated program of protein synthesis. As a consequence, the cells provide a valuable model for the study of regulation of cell differentiation. Experimentally, the approach will quantitate individual chorion production kinetics and will relate these data to messenger RNA utilization. An analysis of this type may answer questions about how cells finely control the timing and quantities of proteins synthesized and about the mechanisms of differential gene expression.